/*
 * The contents of this file are subject to the terms 
 * of the Common Development and Distribution License 
 * (the License).  You may not use this file except in
 * compliance with the License.
 * 
 * You can obtain a copy of the license at 
 * https://glassfish.dev.java.net/public/CDDLv1.0.html or
 * glassfish/bootstrap/legal/CDDLv1.0.txt.
 * See the License for the specific language governing 
 * permissions and limitations under the License.
 * 
 * When distributing Covered Code, include this CDDL 
 * Header Notice in each file and include the License file 
 * at glassfish/bootstrap/legal/CDDLv1.0.txt.  
 * If applicable, add the following below the CDDL Header, 
 * with the fields enclosed by brackets [] replaced by
 * you own identifying information: 
 * "Portions Copyrighted [year] [name of copyright owner]"
 * 
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 */
package com.sun.appserv.management.client.prefs;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.BufferedWriter;
import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.util.Collection;
import java.util.Collections;
//TBD
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

/** A {@link LoginInfoStore} that reads the information from the default file ".asadminpass"
 * and stores it as a map in the memory. It is not guaranteed that the concurrent
 * modifications will yield consistent results. This class is <i> not </i> thread safe. The
 * serial access has to be ensured by the callers.
 * @since Appserver 9.0
 */
public class MemoryHashLoginInfoStore implements LoginInfoStore {
    
    public static final String DEFAULT_STORE_NAME = ".asadminpass";
    
    private static final BASE64Encoder encoder = new BASE64Encoder();
    private static final BASE64Decoder decoder = new BASE64Decoder();
    
    private Map<HostPortKey, LoginInfo> state;
    private final File store;
    /**
     * Creates a new instance of MemoryHashLoginInfoStore. A side effect of calling
     * this constructor is that if the default store does not exist, it will be created.
     * This does not pose any harm or surprises.
     */
    public MemoryHashLoginInfoStore() throws StoreException {
        BufferedReader br = null;
        BufferedWriter bw = null;
        try {
            final File dir = new File (System.getProperty("user.home"));
            store = new File(dir, DEFAULT_STORE_NAME);
            if (!store.exists()) {
                store.createNewFile();
                bw = new BufferedWriter(new FileWriter(store));
                FileMapTransform.writePreamble(bw);
                state = new HashMap<HostPortKey, LoginInfo> ();
            }
            else {
                br = new BufferedReader(new FileReader(store));
                state = FileMapTransform.readAll(br);
            }
        }
        catch(final Exception e) {
            throw new StoreException(e);
        }
        finally {
            try {
                if (br != null)
                    br.close();
            }
            catch(final Exception ee) {}; //ignore
            try {
                if (bw != null)
                    bw.close();
            }
            catch(final Exception ee) {}; //ignore
        }
    }

    public void store(final LoginInfo login) throws StoreException {
        this.store(login, false);
    }

    public void store(final LoginInfo login, boolean overwrite) throws StoreException {
        if (login == null)
            throw new IllegalArgumentException("null_arg");
        final String host = login.getHost();
        final int port    = login.getPort();
        if (!overwrite && this.exists(host, port)) {
            throw new StoreException("Login exists for host: " + host + " port: " + port);
        }
        final HostPortKey key = new HostPortKey(host, port);
        final LoginInfo old   = state.get(key);
        state.put(key, login);
        //System.out.println("committing: " + login);
        commit(key, old);
        protect();
    }

    public void remove(final String host, final int port) {
        final HostPortKey key = new HostPortKey(host, port);
        final LoginInfo gone  = state.remove(key);
        commit(key, gone);
    }

    public LoginInfo read(String host, int port) {
        final HostPortKey key = new HostPortKey(host, port);
        final LoginInfo login = state.get(key); //no need to access disk
        return ( login );
    }

    public boolean exists(String host, int port) {
        final HostPortKey key = new HostPortKey(host, port);
        final boolean exists  = state.containsKey(key); //no need to access disk
        return ( exists );
    }

    public int size() {
        return ( state.size() ); // no need to access disk
    }

    public Collection<LoginInfo> list() {
        final Collection<LoginInfo> logins = state.values(); // no need to access disk
        return (Collections.unmodifiableCollection(logins) );
    }

    public String getName() {
        return ( store.getAbsoluteFile().getAbsolutePath() );
    }
    
    ///// PRIVATE METHODS /////
    private void commit(final HostPortKey key, LoginInfo old) {
        BufferedWriter writer = null;
        try {
            //System.out.println("before commit");
            writer = new BufferedWriter(new FileWriter(store));
            FileMapTransform.writeAll(state.values(), writer);
        }
        catch(final Exception e) {
            state.put(key, old); //try to roll back, first memory
            try { // then disk, if the old value is not null
                if (old != null) {
                    writer = new BufferedWriter(new FileWriter(store));
                    FileMapTransform.writeAll(state.values(), writer);
                }
            }
            catch(final Exception ae) {
                throw new RuntimeException("catastrophe, can't write it to file");
            }//ignore, can't do much
        }
        finally {
            try {
                writer.close();
            } catch(final Exception ee) {} //ignore
        }
    }
    
    private void protect()
    {
        /*
             note: if this is Windows we still try 'chmod' -- they may have MKS or
            some other UNIXy package for Windows.
            cacls is too dangerous to use because it requires a "Y" to be written to
            stdin of the cacls process.  If cacls doesn't exist or if they are using         
            a non-NTFS file system we would hang here forever.
         */
        try
        {
            if(store == null || !store.exists())
                return;

            ProcessBuilder pb = new ProcessBuilder("chmod", "0600", store.getAbsolutePath());
            pb.start();
        }
        catch(Exception e)
        {
            // we tried...
        }
    }

    private static class FileMapTransform {
        private FileMapTransform() {} //disallow
        static Map<HostPortKey, LoginInfo> readAll(final BufferedReader reader) throws IOException, URISyntaxException {
            String line = null;
            final Map<HostPortKey, LoginInfo> map = new HashMap<HostPortKey, LoginInfo> ();
            while ((line = reader.readLine()) != null) {
                if (line.startsWith("#"))
                    continue; //ignore comments
                final int si = line.indexOf(' '); //index of space
                if (si == -1)
                    throw new IOException("Error: invalid record: " + line);
                final URI uri         = new URI(line.substring(0, si));
                final String encp     = line.substring(si+1, line.length());
                final HostPortKey key = uri2Key(uri);
                final LoginInfo value = line2LoginInfo(uri, encp);
                map.put(key, value);
            }
            return ( map );
        }
        static void writeAll(final Collection<LoginInfo> logins, final BufferedWriter writer) throws IOException, URISyntaxException {
            writePreamble(writer);
            //write out sorted, because not more than 100 logins are expected to be there
            final List<LoginInfo> list = new ArrayList<LoginInfo>(logins);
            Collections.sort(list);
            final Iterator<LoginInfo> it = list.iterator();
            while (it.hasNext()) {
                final LoginInfo login = it.next();
                //System.out.println("wrote: " + login);
                writeOne(login, writer);
            }
        }
        private static void writeOne(final LoginInfo login, final BufferedWriter writer) throws IOException, URISyntaxException {
            writer.write(login2Line(login));
            writer.newLine();            
        }
        static final HostPortKey uri2Key(final URI uri) {
            final String host     = uri.getHost();
            final int port        = uri.getPort();
            final HostPortKey key = new HostPortKey(host, port);
            return ( key );
        }
        static final LoginInfo line2LoginInfo(final URI uri, final String encp) throws IOException {
            final String host     = uri.getHost();
            final int port        = uri.getPort();
            final String user     = uri.getUserInfo();
            final String password = new String(decoder.decodeBuffer(encp));
            return ( new LoginInfo(host, port, user, password) );
        }
        static final String login2Line(final LoginInfo login) throws IOException, URISyntaxException {
            final String scheme   = "asadmin";
            final String host     = login.getHost();
            final int port        = login.getPort();
            final String user     = login.getUser();            
            final String path     = null;
            final String query    = null;
            final String frag     = null;
            final URI uri         = new URI(scheme, user, host, port, path, query, frag);
            final String password = login.getPassword();
            final String encp     = encoder.encode(password.getBytes());
            final String line     = uri.toString() + ' ' + encp;
            
            return ( line );
        }
        static void writePreamble(final BufferedWriter bw) throws IOException {
            final String preamble = "# Do not edit this file by hand. Use login interface instead.";
            bw.write(preamble);
            bw.newLine();
        }
    }
    
    private static class HostPortKey {
        private final String host;
        private final int port;
        HostPortKey(final String host, final int port) {
            this.host = host;
            this.port = port;
        }
        public boolean equals(final Object other) {
            boolean same = false;
            if (other instanceof HostPortKey) {
                final HostPortKey that = (HostPortKey)other;
                same = this.host.equals(that.host) && this.port == that.port;
            }
            return ( same );
        }
        public int hashCode() {
            return ( (int) (53 * host.hashCode() + 31 * port) );
        }
    }
}